Swedish patent application No. 8003185-9 describes a mobile chipper which is equipped with a special device comprising a cutter drum having cam-like cut strips which cooperate with a complementary counter member in order to disintergrate branches and other parts of trees that turn across the feed direction after the actual chipping has been carried out in a chipper rotor. However, such a device requires more space for the chipper, and extra bearings and drive mechanisms for the special device.
Swedish patent application No. 7506376-8 discloses a wood chipper which is provided with a permanent lattice plate, whereby such material which cannot pass through the lattice plate is returned by the chipper drum to the chipping site while the material passing through the lattice plate is caught on a screen plate for screening. The employment of a permanent lattice is also described in Swedish patent specification No. 6608604-2.